1. Field of the Invention
The present invention relates to a nonwoven fabric, a nonwoven fabric manufacturing method, and a nonwoven fabric manufacturing apparatus.
2. Related Art
Conventionally, nonwoven fabrics have been used in a wide range of fields including sanitary goods such as disposable diapers and sanitary napkins, cleaning goods such as wipers, and medical supplies such as masks. As described above, nonwoven fabrics have been used in various different fields; however, it is necessary to manufacture them so as to have properties and structures suitable for application of each product if they are actually applied in products in each field.
Nonwoven fabrics are manufactured by, for example, forming a fiber layer (fiber web) by means of a dry method, a wet process, or the like, and bonding fibers in the fiber layer to each other by means of a chemical bonding method, a thermal bonding method, or the like. In a process of bonding the fibers used for forming the fiber layer, methods of applying external physical forces to the fiber layer exist such as a method of repeatedly sticking multiple needles into the fiber layer, a method of jetting streams of water, and other related methods.
Nevertheless, the aforementioned methods are merely used for interlacing fibers, and not for adjusting the orientation and location of fibers in a fiber layer, shape of the fiber layer, or the like. In short, simple sheet-shaped nonwoven fabrics have been manufactured by means of these aforementioned methods.
As described above, there is a problem in that fiber orientation, location, and shape of nonwoven fabrics may not be easily adjusted in an ordinary nonwoven fabric manufacturing process. More specifically, there are problems in that it is difficult to adjust one or more of fiber orientation, fiber density, and basis weight of a fiber layer, and it is difficult to form one or more of groove portions, openings, and protrusions.
To solve the aforementioned problems, for example, a method of deforming a fiber web in the same irregular shape as that of a conveyer by arranging the fiber web containing thermoplastic fibers between a pair of breathable conveyers, which is a pair of breathable conveyers vertically arranged as viewed from a vertical direction, and the surface of at least one of the breathable conveyers is formed in an irregular shape, and directing air onto the surface of the fiber web while conveying the fiber web supported by the pair of breathable conveyers is disclosed in Japanese Unexamined Patent Application Publication No. Hei b 2-229255 (hereinafter referred to as Patent Document 1).
In the case of Patent Document 1, a fiber web is deformed in the same irregular shape as that of a conveyer by supporting the fiber web by way of a pair of breathable conveyers, with the surface of at least one of the breathable conveyers being formed in an irregular shape, and directing air onto one side of the supported fiber web.
In other words, in the nonwoven fabric manufacturing method (nonwoven fabric) according to Patent Document 1, there is a problem in that a pair of breathable conveyers, which supports a fiber web from above and below as viewed from a vertical direction, is needed in order to form a fiber web in an irregular shape. In addition, there is another problem in that the fiber web can only be formed in the same irregular shape as that of the conveyers. That is, there is a problem in that the fiber web may only be deformed into a specified irregular shape by way of the breathable conveyers formed in specified irregular shapes. Moreover, there is another problem in that it is difficult to adjust fiber orientation, fiber density, or basis weight. These are problems of the present invention.